Hydrocarbon refrigerant compositions and uses thereof

ABSTRACT

The present invention relates to compositions for use in refrigeration and air-conditioning systems comprising at least one hydrocarbon, and which are also useful in systems employing a centrifugal compressor The are useful in processes for producing cooling or heat or as heat transfer fluids.

CROSS REFERENCE(S) TO RELATED APPLICATION(S)

This application claims the priority benefit of U.S. ProvisionalApplication 60/584,785, filed Jun. 29, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to compositions for use in refrigerationand air-conditioning systems comprising at least one hydrocarbon.Further, the present invention relates to compositions for use inrefrigeration and air-conditioning systems employing a centrifugalcompressor comprising at least one hydrocarbon. The compositions of thepresent invention are useful in processes for producing refrigeration orheat or as heat transfer fluids.

2. Description of Related Art

The refrigeration industry has been working for the past few decades tofind replacement refrigerants for the ozone depletingchlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) beingphased out as a result of the Montreal Protocol. The solution for mostrefrigerant producers has been the commercialization ofhydrofluorocarbon (HFC) refrigerants. The new HFC refrigerants, HFC-134abeing the most widely used at this time, have zero ozone depletionpotential and thus are not affected by the current regulatory phase-outas a result of the Montreal Protocol.

Further, environmental regulations may ultimately cause global phase-outof certain HFC refrigerants. Currently, the automobile industry isfacing regulations relating to global warming potential (GWP) forrefrigerants used in mobile air-conditioning. Therefore, there is agreat current need to identify new refrigerants with reduced GWP for theautomobile air-conditioning market. Should the regulations be morebroadly applied in the future, an even greater need will be felt for lowGWP refrigerants that can be used in all areas of the refrigeration andair-conditioning industry.

Currently proposed replacement refrigerants for HFC-134a includeHFC-152a, pure hydrocarbons such as butane or propane, or “natural”refrigerants such as CO₂ or ammonia. Many of these suggestedreplacements are toxic, flammable, and/or have low energy efficiency.Therefore, new alternatives are constantly being sought.

The present invention provides refrigerant compositions and heattransfer fluids having unique characteristics to meet the demands of lowor zero ozone depletion potential, and lower GWP.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to refrigerant or heat transfer fluidcomposition comprising at least one hydrocarbon selected from the groupconsisting of:

2,2-dimethylbutane;

2,3-dimethylbutane;

2,3-dimethylpentane;

2-methylhexane;

3-methylhexane;

2-methylpentane;

3-ethylpentane;

3-methylpentane;

cyclohexane;

cyclopentane;

n-heptane;

methylcyclopentane;

n-pentane; and

n-hexane.

The present invention further relates to the above listed compositionsspecifically for use in refrigeration or air-conditioning systemsemploying a centrifugal compressor; a multi-stage or 2-stage centrifugalcompressor; or a single pass/single slab heat exchanger.

The present invention further relates to processes for producingrefrigeration, heat, and transfer of heat from a heat source to a heatsink using the present inventive compositions.

DETAILED DESCRIPTION OF THE INVENTION

The refrigerant and heat transfer fluid compositions of the presentinvention comprise at least one hydrocarbon. The refrigerant and heattransfer fluid compositions of the present invention may comprise asingle hydrocarbon or may be a combination or mixture comprising morethan one hydrocarbon.

The hydrocarbons of the present invention comprise compounds containinghydrogen and carbon. Such hydrocarbons may be straight chain, branchedchain or cyclic compounds and have from about 5 to about 10 carbonatoms. Preferred hydrocarbons have from 5 to 7 carbon atoms.Representative hydrocarbons of the present invention are listed inTable 1. TABLE 1 CAS Chemical Name Chemical Formula Reg. No. 2,2-CH₃CH₂C(CH₃)₃ 75-83-2 dimethylbutane 2,3- CH₃CH(CH₃)CH(CH₃)CH₃ 79-29-8dimethylbutane 2,3- CH₃CH(CH₃)CH(CH₃)CH₂CH₃ 565-59-3 dimethylpentane2-methylhexane CH₃CH(CH₃)CH₂CH₂CH₂CH₃ 591-76-4 3-methylhexaneCH₃CH₂CH(CH₃)CH₂CH₂CH₃ 589-34-4 2-methylpentane CH₃CH(CH₃)CH₂CH₂CH₃107-83-5 3-ethylpentane CH₃CH₂CH(CH₂CH₃)CH₂CH₃ 617-78-7 3-methylpentaneCH₃CH₂CH(CH₃)CH₂CH₃ 96-14-0 cyclohexane cyclo-CH₂CH₂CH₂CH₂CH₂CH₂CH₂—110-82-7 cyclopentane cyclo-CH₂CH₂CH₂CH₂CH₂CH₂— 287-92-3 n-heptaneCH₃CH₂CH₂CH₂CH₂CH₂CH₃ 142-82-5 methyl- cyclo-CH₂CH(CH₃)CH₂CH₂CH₂—96-37-7 cyclopentane n-pentane CH₃CH₂CH₂CH₂CH₃ 109-66-0 n-hexaneCH₃CH₂CH₂CH₂CH₂CH₃ 110-54-3

The compounds listed in Table 1 are available commercially or may beprepared by processes known in the art.

The compositions of the present invention that are mixtures may beprepared by any convenient method to combine the desired amounts of theindividual components. A preferred method is to weigh the desiredcomponent amounts and thereafter combine the components in anappropriate vessel. Agitation may be used, if desired.

Compositions of the present invention have low or zero ozone depletionpotential and low global warming potential. The hydrocarbons of thepresent invention, alone or in mixtures, will have global warmingpotentials lower than many HFC refrigerants currently in use.

The refrigerant or heat transfer fluid compositions of the presentinvention include:

-   2,2-dimethylbutane;-   2,3-dimethylbutane;-   2,3-dimethylpentane;-   2-methylhexane;-   3-methylhexane;-   2-methylpentane;-   3-ethylpentane;-   3-methylpentane;-   cyclohexane;-   cyclopentane;-   n-heptane;-   methylcyclopentane;-   n-pentane;-   n-hexane; or-   combinations thereof.

The compositions of the present invention may further comprise about0.01 weight percent to about 5 weight percent of a stabilizer, freeradical scavenger or antioxidant. Such additives include but are notlimited to, nitromethane, hindered phenols, hydroxylamines, thiols,phosphites, or lactones. Single additives or combinations may be used.

The compositions of the present invention may further comprise about0.01 weight percent to about 5 weight percent of a water scavenger(drying compound). Such water scavengers may comprise ortho esters suchas trimethyl-, triethyl-, or tripropylorthoformate.

The compositions of the present invention may further comprise anultra-violet (UV) dye and optionally a solubilizing agent. The UV dye isa useful component for detecting leaks of the refrigerant and heattransfer fluid compositions by permitting one to observe thefluorescence of the dye in the refrigerant or heat transfer fluidcompositions at a leak point or in the vicinity of refrigeration orair-conditioning apparatus. One may observe the fluorescence of the dyeunder an ultra-violet light. Solubilizing agents may be needed toincrease solubility of such UV dyes in some refrigerants and heattransfer fluids.

By “ultra-violet” dye is meant a UV fluorescent composition that absorbslight in the ultra-violet or “near” ultra-violet region of theelectromagnetic spectrum. The fluorescence produced by the UVfluorescent dye under illumination by a UV light that emits radiationwith wavelength anywhere from 10 nanometer to 750 nanometer may bedetected. Therefore, if refrigerant or heat transfer fluid containingsuch a UV fluorescent dye is leaking from a given point in arefrigeration or air-conditioning apparatus, the fluorescence can bedetected at the leak point. Such UV fluorescent dyes include but are notlimited to naphthalimides, perylenes, coumarins, anthracenes,phenanthracenes, xanthenes, thioxanthenes, naphthoxanthenes,fluoresceins, and derivatives or combinations thereof. Solubilizingagents of the present invention comprise at least one compound selectedfrom the group consisting of hydrocarbons, hydrocarbon ethers,polyoxyalkylene glycol ethers, amides, nitriles, ketones, chlorocarbons,esters, lactones, aryl ethers, fluoroethers and 1,1,1-trifluoroalkanes.

Hydrocarbon solubilizing agents of the present invention comprisehydrocarbons including straight chained, branched chain or cyclicalkanes or alkenes containing 16 or fewer carbon atoms and only hydrogenwith no other functional groups. Representative hydrocarbon solubilizingagents comprise propane, propylene, cyclopropane, n-butane, isobutane,n-pentane, octane, decane, and hexadecane. It should be noted that therefrigerant and the solubilizing agent may not be the same hydrocarbon.

Hydrocarbon ether solubilizing agents of the present invention compriseethers containing only carbon, hydrogen and oxygen, such as dimethylether (DME).

Polyoxyalkylene glycol ether solubilizing agents of the presentinvention are represented by the formula R¹[(OR²)_(x)OR³]_(y), wherein xis an integer from 1-3; y is an integer from 1-4; R¹ is selected fromhydrogen and aliphatic hydrocarbon radicals having 1 to 6 carbon atomsand y bonding sites; R² is selected from aliphatic hydrocarbyleneradicals having from 2 to 4 carbon atoms; R³ is selected from hydrogen,and aliphatic and alicyclic hydrocarbon radicals having from 1 to 6carbon atoms; at least one of R¹ and R³ is selected from saidhydrocarbon radical; and wherein said polyoxyalkylene glycol ethers havea molecular weight of from about 100 to about 300 atomic mass units. Asused herein, bonding sites mean radical sites available to form covalentbonds with other radicals. Hydrocarbylene radicals mean divalenthydrocarbon radicals.

In the present invention, preferable polyoxyalkylene glycol ethersolubilizing agents are represented by R¹[(OR²)_(x)OR³]_(y) wherein x ispreferably 1-2; y is preferably 1; R¹ and R³ are preferablyindependently selected from hydrogen and aliphatic hydrocarbon radicalshaving 1 to 4 carbon atoms; R² is preferably selected from aliphatichydrocarbylene radicals having from 2 or 3 carbon atoms, most preferably3 carbon atoms; the polyoxyalkylene glycol ether molecular weight ispreferably from about 100 to about 250 atomic mass units, mostpreferably from about 125 to about 250 atomic mass units. The R¹ and R³hydrocarbon radicals having 1 to 6 carbon atoms may be linear, branchedor cyclic. Representative R¹ and R³ hydrocarbon radicals include methyl,ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,pentyl, isopentyl, neopentyl, tert-pentyl, cyclopentyl, and cyclohexyl.Where free hydroxyl radicals on the present polyoxyalkylene glycol ethersolubilizing agents may be incompatible with certain compressionrefrigeration apparatus materials of construction (e.g. Mylar®), R¹ andR³ are preferably aliphatic hydrocarbon radicals having 1 to 4 carbonatoms, most preferably 1 carbon atom. The R² aliphatic hydrocarbyleneradicals having from 2 to 4 carbon atoms form repeating oxyalkyleneradicals —(OR²)_(x)— that include oxyethylene radicals, oxypropyleneradicals, and oxybutylene radicals. The oxyalkylene radical comprisingR² in one polyoxyalkylene glycol ether solubilizing agent molecule maybe the same, or one molecule may contain different R² oxyalkylenegroups. The present polyoxyalkylene glycol ether solubilizing agentspreferably comprise at least one oxypropylene radical. Where R¹ is analiphatic or alicyclic hydrocarbon radical having 1 to 6 carbon atomsand y bonding sites, the radical may be linear, branched or cyclic.Representative R¹ aliphatic hydrocarbon radicals having two bondingsites include, for example, an ethylene radical, a propylene radical, abutylene radical, a pentylene radical, a hexylene radical, acyclopentylene radical and a cyclohexylene radical. Representative R¹aliphatic hydrocarbon radicals having three or four bonding sitesinclude residues derived from polyalcohols, such as trimethylolpropane,glycerin, pentaerythritol, 1,2,3-trihydroxycyclohexane and1,3,5-trihydroxycyclohexane, by removing their hydroxyl radicals.

Representative polyoxyalkylene glycol ether solubilizing agents includebut are not limited to: CH₃OCH₂CH(CH₃)O(H or CH₃) (propylene glycolmethyl (or dimethyl) ether), CH₃O[CH₂CH(CH₃)O]₂(H or CH₃) (dipropyleneglycol methyl (or dimethyl) ether), CH₃O[CH₂CH(CH₃)O]₃(H or CH₃)(tripropylene glycol methyl (or dimethyl) ether), C₂H₅OCH₂CH(CH₃)O(H orC₂H₅) (propylene glycol ethyl (or diethyl) ether), C₂H₅O[CH₂CH(CH₃)O]₂(Hor C₂H₅) (dipropylene glycol ethyl (or diethyl) ether),C₂H₅O[CH₂CH(CH₃)O]₃(H or C₂H₅) (tripropylene glycol ethyl (or diethyl)ether), C₃H₇OCH₂CH(CH₃)O(H or C₃H₇) (propylene glycol n-propyl (ordi-n-propyl) ether), C₃H₇O[CH₂CH(CH₃)O]₂(H or C₃H₇) (dipropylene glycoln-propyl (or di-n-propyl) ether), C₃H₇O[CH₂CH(CH₃)O]₃(H or C₃H₇)(tripropylene glycol n-propyl (or di-n-propyl) ether), C₄H₉OCH₂CH(CH₃)OH(propylene glycol n-butyl ether), C₄H₉O[CH₂CH(CH₃)O]₂(H or C₄H₉)(dipropylene glycol n-butyl (or di-n-butyl) ether),C₄H₉O[CH₂CH(CH₃)O]₃(H or C₄H₉) (tripropylene glycol n-butyl (ordi-n-butyl) ether), (CH₃)₃COCH₂CH(CH₃)OH (propylene glycol t-butylether), (CH₃)₃CO[CH₂CH(CH₃)O]₂(H or (CH₃)₃) (dipropylene glycol t-butyl(or di-t-butyl)ether), (CH₃)₃CO[CH₂CH(CH₃)O]₃(H or (CH₃)₃) (tripropyleneglycol t-butyl (or di-t-butyl) ether), C₅H₁₁OCH₂CH(CH₃)OH (propyleneglycol n-pentyl ether), C₄H₉OCH₂CH(C₂H₅)OH (butylene glycol n-butylether), C₄H₉O[CH₂CH(C₂H₅)O]₂H (dibutylene glycol n-butyl ether),trimethylolpropane tri-n-butyl ether (C₂H₅C(CH₂O(CH₂)₃CH₃)₃) andtrimethylolpropane di-n-butyl ether (C₂H₅C(CH₂OC(CH₂)₃CH₃)₂CH₂OH).

Amide solubilizing agents of the present invention comprise thoserepresented by the formulae R¹C(O)NR²R³ and cyclo-[R⁴C(O)N(R⁵)—],wherein R¹, R², R³ and R⁵ are independently selected from aliphatic andalicyclic hydrocarbon radicals having from 1 to 12 carbon atoms; R⁴ isselected from aliphatic hydrocarbylene radicals having from 3 to 12carbon atoms; and wherein said amides have a molecular weight of fromabout 100 to about 300 atomic mass units. The molecular weight of saidamides is preferably from about 160 to about 250 atomic mass units. R¹,R², R³ and R⁵ may optionally include substituted hydrocarbon radicals,that is, radicals containing non-hydrocarbon substituents selected fromhalogens (e.g., fluorine, chlorine) and alkoxides (e.g. methoxy). R¹,R², R³ and R⁵ may optionally include heteroatom-substituted hydrocarbonradicals, that is, radicals, which contain the atoms nitrogen (aza-),oxygen (oxa-) or sulfur (thia-) in a radical chain otherwise composed ofcarbon atoms. In general, no more than three non-hydrocarbonsubstituents and heteroatoms, and preferably no more than one, will bepresent for each 10 carbon atoms in R¹⁻³, and the presence of any suchnon-hydrocarbon substituents and heteroatoms must be considered inapplying the aforementioned molecular weight limitations. Preferredamide solubilizing agents consist of carbon, hydrogen, nitrogen andoxygen. Representative R¹, R², R³ and R5 aliphatic and alicyclichydrocarbon radicals include methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl,tert-pentyl, cyclopentyl, cyclohexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl and their configurational isomers. A preferredembodiment of amide solubilizing agents are those wherein R⁴ in theaforementioned formula cyclo-[R⁴C(O)N(R⁵)—] may be represented by thehydrocarbylene radical (CR⁶R⁷)_(n), in other words, the formulacyclo-[(CR⁶R⁷)_(n)C(O)N(R⁵)—] wherein the previously-stated values formolecular weight apply; n is an integer from 3 to 5; R⁵ is a saturatedhydrocarbon radical containing 1 to 12 carbon atoms; R⁶ and R⁷ areindependently selected (for each n) by the rules previously offereddefining R¹⁻³. In the lactams represented by the formula:cyclo-[(CR⁶R⁷)_(n)C(O)N(R⁵)—], all R⁶ and R⁷ are preferably hydrogen, orcontain a single saturated hydrocarbon radical among the n methyleneunits, and R⁵ is a saturated hydrocarbon radical containing 3 to 12carbon atoms. For example, 1 -(saturated hydrocarbonradical)-5-methylpyrrolidin-2-ones.

Representative amide solubilizing agents include but are not limited to:1-octylpyrrolidin-2-one, 1-decylpyrrolidin-2-one,1-octyl-5-methylpyrrolidin-2-one, 1-butylcaprolactam,1-cyclohexylpyrrolidin-2-one, 1-butyl-5-methylpiperid-2-one,1-pentyl-5-methylpiperid-2-one, 1-hexylcaprolactam,1-hexyl-5-methylpyrrolidin-2-one, 5-methyl-1-pentylpiperid-2-one,1,3-dimethylpiperid-2-one, 1-methylcaprolactam,1-butyl-pyrrolidin-2-one, 1,5-dimethylpiperid-2-one,1-decyl-5-methylpyrrolidin-2-one, 1-dodecylpyrrolid-2-one,N,N-dibutylformamide and N,N-diisopropylacetamide.

Ketone solubilizing agents of the present invention comprise ketonesrepresented by the formula R¹C(O)R², wherein R¹ and R² are independentlyselected from aliphatic, alicyclic and aryl hydrocarbon radicals havingfrom 1 to 12 carbon atoms, and wherein said ketones have a molecularweight of from about 70 to about 300 atomic mass units. R¹ and R² insaid ketones are preferably independently selected from aliphatic andalicyclic hydrocarbon radicals having 1 to 9 carbon atoms. The molecularweight of said ketones is preferably from about 100 to 200 atomic massunits. R¹ and R² may together form a hydrocarbylene radical connectedand forming a five, six, or seven-membered ring cyclic ketone, forexample, cyclopentanone, cyclohexanone, and cycloheptanone. R¹ and R²may optionally include substituted hydrocarbon radicals, that is,radicals containing non-hydrocarbon substituents selected from halogens(e.g., fluorine, chlorine) and alkoxides (e.g. methoxy). R¹ and R² mayoptionally include heteroatom-substituted hydrocarbon radicals, that is,radicals, which contain the atoms nitrogen (aza-), oxygen (keto-, oxa-)or sulfur (thia-) in a radical chain otherwise composed of carbon atoms.In general, no more than three non-hydrocarbon substituents andheteroatoms, and preferably no more than one, will be present for each10 carbon atoms in R¹ and R², and the presence of any suchnon-hydrocarbon substituents and heteroatoms must be considered inapplying the aforementioned molecular weight limitations. RepresentativeR¹ and R² aliphatic, alicyclic and aryl hydrocarbon radicals in thegeneral formula R¹C(O)R² include methyl, ethyl, propyl, isopropyl,butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl,tert-pentyl, cyclopentyl, cyclohexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl and their configurational isomers, as well as phenyl,benzyl, cumenyl, mesityl, tolyl, xylyl and phenethyl.

Representative ketone solubilizing agents include but are not limitedto: 2-butanone, 2-pentanone, acetophenone, butyrophenone, hexanophenone,cyclohexanone, cycloheptanone, 2-heptanone, 3-heptanone,5-methyl-2-hexanone, 2-octanone, 3-octanone, diisobutyl ketone,4-ethylcyclohexanone, 2-nonanone, 5-nonanone, 2-decanone, 4-decanone,2-decalone, 2-tridecanone, dihexyl ketone and dicyclohexyl ketone.

Nitrile solubilizing agents of the present invention comprise nitrilesrepresented by the formula R¹CN, wherein R¹ is selected from aliphatic,alicyclic or aryl hydrocarbon radicals having from 5 to 12 carbon atoms,and wherein said nitriles have a molecular weight of from about 90 toabout 200 atomic mass units. R¹ in said nitrile solubilizing agents ispreferably selected from aliphatic and alicyclic hydrocarbon radicalshaving 8 to 10 carbon atoms. The molecular weight of said nitrilesolubilizing agents is preferably from about 120 to about 140 atomicmass units. R¹ may optionally include substituted hydrocarbon radicals,that is, radicals containing non-hydrocarbon substituents selected fromhalogens (e.g., fluorine, chlorine) and alkoxides (e.g. methoxy). R¹ mayoptionally include heteroatom-substituted hydrocarbon radicals, that is,radicals, which contain the atoms nitrogen (aza-), oxygen (keto-, oxa-)or sulfur (thia-) in a radical chain otherwise composed of carbon atoms.In general, no more than three non-hydrocarbon substituents andheteroatoms, and preferably no more than one, will be present for each10 carbon atoms in R¹, and the presence of any such non-hydrocarbonsubstituents and heteroatoms must be considered in applying theaforementioned molecular weight limitations. Representative R¹aliphatic, alicyclic and aryl hydrocarbon radicals in the generalformula R¹CN include pentyl, isopentyl, neopentyl, tert-pentyl,cyclopentyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyland their configurational isomers, as well as phenyl, benzyl, cumenyl,mesityl, tolyl, xylyl and phenethyl. Representative nitrile solubilizingagents include but are not limited to: 1-cyanopentane,2,2-dimethyl-4-cyanopentane, 1-cyanohexane, 1-cyanoheptane,1-cyanooctane, 2-cyanooctane, 1-cyanononane, 1-cyanodecane,2-cyanodecane, 1-cyanoundecane and 1-cyanododecane.

Chlorocarbon solubilizing agents of the present invention comprisechlorocarbons represented by the formula RCl_(x), wherein x is 1 or 2; Ris selected from aliphatic and alicyclic hydrocarbon radicals having 1to 12 carbon atoms; and wherein said chlorocarbons have a molecularweight of from about 100 to about 200 atomic mass units. The molecularweight of said chlorocarbon solubilizing agents is preferably from about120 to 150 atomic mass units. Representative R aliphatic and alicyclichydrocarbon radicals in the general formula RCl_(x) include methyl,ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,pentyl, isopentyl, neopentyl, tert-pentyl, cyclopentyl, cyclohexyl,heptyl, octyl, nonyl, decyl, undecyl, dodecyl and their configurationalisomers.

Representative chlorocarbon solubilizing agents include but are notlimited to: 3-(chloromethyl)pentane, 3-chloro-3-methylpentane,1-chlorohexane, 1,6-dichlorohexane, 1-chloroheptane, 1-chlorooctane,1-chlorononane, 1-chlorodecane, and 1,1,1-trichlorodecane.

Ester solubilizing agents of the present invention comprise estersrepresented by the general formula R¹C(O)OR², wherein R¹ and R² areindependently selected from linear and cyclic, saturated andunsaturated, alkyl and aryl radicals. Preferred esters consistessentially of the elements C, H and O, have a molecular weight of fromabout 80 to about 550 atomic mass units.

Representative esters include but are not limited to:(CH₃)₂CHCH₂O(O)C(CH₂)₂₄(O)COCH₂CH(CH₃)₂ (diisobutyl dibasic ester),ethyl hexanoate, ethyl heptanoate, n-butyl propionate, n-propylpropionate, ethyl benzoate, di-n-propyl phthalate, benzoic acidethoxyethyl ester, dipropyl carbonate, “Exxate 700” (a commercial C₇alkyl acetate), “Exxate 800” (a commercial C₈ alkyl acetate), dibutylphthalate, and tert-butyl acetate.

Lactone solubilizing agents of the present invention comprise lactonesrepresented by structures [A], [B], and [C]:

These lactones contain the functional group —C(O)O— in a ring of six(A), or preferably five atoms (B), wherein for structures [A] and [B],R₁ through R₈ are independently selected from hydrogen or linear,branched, cyclic, bicyclic, saturated and unsaturated hydrocarbylradicals. Each R₁ through R₈ may be connected forming a ring withanother R₁ through R₈. The lactone may have an exocyclic alkylidenegroup as in structure [C], wherein R₁ through R₆ are independentlyselected from hydrogen or linear, branched, cyclic, bicyclic, saturatedand unsaturated hydrocarbyl radicals. Each R₁ though R₆ may be connectedforming a ring with another R₁ through R₆. The lactone solubilizingagents have a molecular weight range of from about 80 to about 300atomic mass units, preferred from about 80 to about 200 atomic massunits.

Representative lactone solubilizing agents include but are not limitedto the compounds listed in Table 2. TABLE 2 Molecular Molecular AdditiveMolecular Structure Formula Weight (amu) (E,Z)-3-ethylidene-5-methyl-dihydro-furan-2-one

C₇H₁₀O₂ 126 (E,Z)-3-propylidene-5-methyl- dihydro-furan-2-one

C₈H₁₂O₂ 140 (E,Z)-3-butylidene-5-methyl- dihydro-furan-2-one

C₉H₁₄O₂ 154 (E,Z)-3-pentylidene-5-methyl- dihydro-furan-2-one

C₁₀H₁₆O₂ 168 (E,Z)-3-Hexylidene-5-methyl- dihydro-furan-2-one

C₁₁H₁₈O₂ 182 (E,Z)-3-Heptylidene-5-methyl- dihydro-furan-2-one

C₁₂H₂₀O₂ 196 (E,Z)-3-octylidene-5-methyl- dihydro-furan-2-one

C₁₃H₂₂O₂ 210 (E,Z)-3-nonylidene-5-methyl- dihydro-furan-2-one

C₁₄H₂₄O₂ 224 (E,Z)-3-decylidene-5-methyl- dihydro-furan-2-one

C₁₅H₂₆O₂ 238 (E,Z)-3-(3,5,5-trimethylhexylidene)-5-methyl-dihydrofuran-2-one

C₁₄H₂₄O₂ 224 (E,Z)-3-cyclohexytmethylidene-5- methyl-dihydrofuran-2-one

C₁₂H₁₈O₂ 194 gamma-octalactone

C₈H₁₄O₂ 142 gamma-nonalactone

C₉H₁₆O₂ 156 gamma-decalactone

C₁₀H₁₈O₂ 170 gamma-undecalactone

C₁₁H₂₀O₂ 184 gamma-dodecalactone

C₁₂H₂₂O₂ 198 3-hexyldihydro-furan-2-one

C₁₀H₁₈O₂ 170 3-heptyldihydro-furan-2-one

C₁₁H₂₀O₂ 184 cis-3-ethyl-5-methyl-dihydro-furan- 2-one

C₇H₁₂O₂ 128 cis-(3-propyl-5-methyl)-dihydro- furan-2-one

C₈H₁₄O₂ 142 cis-(3-butyl-5-methyl)-dihydro- furan-2-one

C₉H₁₆O₂ 156 cis-(3-pentyl-5-methyl)-dihydro- furan-2-one

C₁₀H₁₈O₂ 170 cis-3-hexyl-5-methyl-dihydro-furan- 2-one

C₁₁H₂₀O₂ 184 cis-3-heptyl-5-methyl-dihydro- furan-2-one

C₁₂H₂₂O₂ 198 cis-3-octyl-5-methyl-dihydro-furan- 2-one

C₁₃H₂₄O₂ 212 cis-3-(3,5,5-trimethylhexyl)-5- methyl-dihydro-furan-2-one

C₁₄H₂₆O₂ 226 cis-3-cyclohexylmethyl-5-methyl- dihydro-furan-2-one

C₁₂H₂₀O₂ 196 5-methyl-5-hexyl-dihydro-furan-2- one

C₁₁H₂₀O₂ 184 5-methyl-5-octyl-dihydro-furan-2- one

C₁₃H₂₄O₂ 212 Hexahydro-isobenzofuran-1-one

C₈H₁₂O₂ 140 delta-decalactone

C₁₀H₁₈O₂ 170 delta-undecalactone

C₁₁H₂₀O₂ 184 delta-dodecalactone

C₁₂H₂₂O₂ 198 mixture of 4-hexyl-dihydrofuran-2- one and3-hexyl-dihydro-furan-2- one

C₁₀H₁₈O₂ 170

Lactone solubilizing agents generally have a kinematic viscosity of lessthan about 7 centistokes at 40° C. For instance, gamma-undecalactone haskinematic viscosity of 5.4 centistokes andcis-(3-hexyl-5-methyl)dihydrofuran-2-one has viscosity of 4.5centistokes, both at 40° C.

Lactone solubilizing agents may be available commercially or prepared bymethods as described in U.S. patent application Ser. No. 10/910,495,filed Aug. 3, 2004, incorporated herein by reference.

Aryl ether solubilizing agents of the present invention comprise arylethers represented by the formula R¹OR², wherein: R¹ is selected fromaryl hydrocarbon radicals having from 6 to 12 carbon atoms; R² isselected from aliphatic hydrocarbon radicals having from 1 to 4 carbonatoms; and wherein said aryl ethers have a molecular weight of fromabout 100 to about 150 atomic mass units. Representative R¹ arylradicals in the general formula R¹OR² include phenyl, biphenyl, cumenyl,mesityl, tolyl, xylyl, naphthyl and pyridyl. Representative R² aliphatichydrocarbon radicals in the general formula R¹OR² include methyl, ethyl,propyl, isopropyl, butyl, isobutyl, sec-butyl and tert-butyl.Representative aromatic ether solubilizing agents include but are notlimited to: methyl phenyl ether (anisole), 1,3-dimethyoxybenzene, ethylphenyl ether and butyl phenyl ether.

Fluoroether solubilizing agents of the present invention comprise thoserepresented by the general formula R¹OCF₂CF₂H, wherein R¹ is selectedfrom aliphatic, alicyclic, and aromatic hydrocarbon radicals having fromabout 5 to about 15 carbon atoms, preferably primary, linear, saturated,alkyl radicals. Representative fluoroether solubilizing agents includebut are not limited to: C₈H₁₇OCF₂CF₂H and C₆H₁₃OCF₂CF₂H. It should benoted that if the refrigerant is a fluoroether, then the solubilizingagent may not be the same fluoroether.

Fluoroether solubilizing agents may further comprise ethers derived fromfluoro-olefins and polyols. The fluoro-olefins may be of the typeCF₂═CXY, wherein X is hydrogen, chlorine or fluorine, and Y is chlorine,fluorine, CF₃ or OR_(f), wherein R_(f) is CF₃, C₂F₅, or C₃F₇.Representative fluoro-olefins are tetrafluoroethylene,chlorotrifluoroethylene, hexafluoropropylene, and perfluoromethylvinylether. The polyols may be linear or branched. Linear polyols may be ofthe type HOCH₂ (CHOH)_(x)(CRR′)_(y)CH₂OH, wherein R and R′ are hydrogen,or CH₃, or C₂H₅ and wherein x is an integer from 0-4, and y is aninteger from 0-4. Branched polyols may be of the typeC(OH)_(t)(R)_(u)(CH2OH)_(v)[(CH2)_(m)CH2OH]_(w), wherein R may behydrogen, CH₃ or C₂H₅, m may be an integer from 0 to 3, t and u may be 0or 1, v and w are integers from 0 to 4, and also wherein t+u+v+w=4.Representative polyols are trimethylol propane, pentaerythritol,butanediol, and ethylene glycol.

1,1,1-Trifluoroalkane solubilizing agents of the present inventioncomprise 1,1,1-trifluoroalkanes represented by the general formulaCF₃R¹, wherein R¹ is selected from aliphatic and alicyclic hydrocarbonradicals having from about 5 to about 15 carbon atoms, preferablyprimary, linear, saturated alkyl radicals. Representative1,1,1-trifluoroalkane solubilizing agents include but are not limitedto: 1,1,1-trifluorohexane and 1,1,1-trifluorododecane.

Solubilizing agents of the present invention may be present as a singlecompound, or may be present as a mixture of more than one solubilizingagent. Mixtures of solubilizing agents may contain two solubilizingagents from the same class of compounds, say two lactones, or twosolubilizing agents from two different classes, such as a lactone and apolyoxyalkylene glycol ether.

In the present compositions comprising refrigerant and UV fluorescentdye, or comprising heat transfer fluid and UV fluorescent dye, fromabout 0.001 weight percent to about 1.0 weight percent of thecompositions is UV dye, preferably from about 0.005 weight percent toabout 0.5 weight percent, and most preferably from 0.01 weight percentto about 0.25 weight percent.

Solubility of these UV fluorescent dyes in refrigerants and heattransfer fluids may be poor. Therefore, methods for introducing thesedyes into the refrigeration or air-conditioning apparatus have beenawkward, costly and time consuming. U.S. Pat. No. RE 36,951 describes amethod, which utilizes a dye powder, solid pellet or slurry of dye thatmay be inserted into a component of the refrigeration orair-conditioning apparatus. As refrigerant and lubricant are circulatedthrough the apparatus, the dye is dissolved or dispersed and carriedthroughout the apparatus. Numerous other methods for introducing dyeinto a refrigeration or air-conditioning apparatus are described in theliterature.

Ideally, the UV fluorescent dye could be dissolved in the refrigerantitself thereby not requiring any specialized method for introduction tothe refrigeration or air-conditioning apparatus. The present inventionrelates to compositions including UV fluorescent dye, which may beintroduced into the system in the refrigerant. The inventivecompositions will allow the storage and transport of dye-containingrefrigerant and heat transfer fluid even at low temperatures whilemaintaining the dye in solution.

In the present compositions comprising refrigerant, UV fluorescent dyeand solubilizing agent, or comprising heat transfer fluid, UVfluorescent dye and solubilizing agent, from about 1 to about 50 weightpercent, preferably from about 2 to about 25 weight percent, and mostpreferably from about 5 to about 15 weight percent of the combinedcomposition is solubilizing agent in the refrigerant or heat transferfluid. In the compositions of the present invention the UV fluorescentdye is present in a concentration from about 0.001 weight percent toabout 1.0 weight percent in the refrigerant or heat transfer fluid,preferably from 0.005 weight percent to about 0.5 weight percent, andmost preferably from 0.01 weight percent to about 0.25 weight percent.

Optionally, commonly used refrigeration or air-conditioning systemadditives may be added, as desired, to compositions of the presentinvention in order to enhance performance and system stability. Theseadditives are known in the field of refrigeration and air-cinditioning,and include, but are not limited to, anti wear agents, extreme pressurelubricants, corrosion and oxidation inhibitors, metal surfacedeactivators, free radical scavengers, and foam control agents. Ingeneral, these additives are present in the inventive compositions insmall amounts relative to the overall composition. Typicallyconcentrations of from less than about 0.1 weight percent to as much asabout 3 weight percent of each additive are used. These additives areselected on the basis of the individual system requirements. Theseadditives include members of the triaryl phosphate family of EP (extremepressure) lubricity additives, such as butylated triphenyl phosphates(BTPP), or other alkylated triaryl phosphate esters, e.g. Syn-0-Ad 8478from Akzo Chemicals, tricresyl phosphates and related compounds.Additionally, the metal dialkyl dithiophosphates (e.g. zinc dialkyldithiophosphate (or ZDDP), Lubrizol 1375 and other members of thisfamily of chemicals may be used in compositions of the presentinvention. Other antiwear additives include natural product oils andasymmetrical polyhydroxyl lubrication additives, such as Synergol TMS(International Lubricants). Similarly, stabilizers such as antioxidants, free radical scavengers, and water scavengers may be employed.Compounds in this category can include, but are not limited to,butylated hydroxy toluene (BHT) and epoxides.

Solubilizing agents such as ketones may have an objectionable odor,which can be masked by addition of an odor masking agent or fragrance.Typical examples of odor masking agents or fragrances may includeEvergreen, Fresh Lemon, Cherry, Cinnamon, Peppermint, Floral or OrangePeel, all commercially available, as well as d-limonene and pinene. Suchodor masking agents may be used at concentrations of from about 0.001%to as much as about 15% by weight based on the combined weight of odormasking agent and solubilizing agent.

The present invention further relates to a method of using therefrigerant or heat transfer fluid compositions further comprisingultraviolet fluorescent dye, and optionally, solubilizing agent, inrefrigeration or air-conditioning apparatus. The method comprisesintroducing the refrigerant or heat transfer fluid composition into therefrigeration or air-conditioning apparatus. This may be done bydissolving the UV fluorescent dye in the refrigerant or heat transferfluid composition in the presence of a solubilizing agent andintroducing the combination into the apparatus. Alternatively, this maybe done by combining solubilizing agent and UV fluorescent dye andintroducing said combination into refrigeration or air-conditioningapparatus containing refrigerant and/or heat transfer fluid. Theresulting composition may be used in the refrigeration orair-conditioning apparatus.

The present invention further relates to a method of using therefrigerant or heat transfer fluid compositions comprising ultravioletfluorescent dye to detect leaks. The presence of the dye in thecompositions allows for detection of leaking refrigerant in therefrigeration or air-conditioning apparatus. Leak detection helps toaddress, resolve or prevent inefficient operation of the apparatus orsystem or equipment failure. Leak detection also helps one containchemicals used in the operation of the apparatus.

The method comprises providing the composition comprising refrigerantand ultra-violet fluorescent dye, or comprising heat transfer fluid andultra-violet fluorescent dye as described herein, and optionally, asolubilizing agent as described herein, to refrigeration andair-conditioning apparatus and employing a suitable means for detectingthe UV fluorescent dye-containing refrigerant. Suitable means fordetecting the dye include, but are not limited to, ultra-violet lamp,often referred to as a “black light” or “blue light”. Such ultra-violetlamps are commercially available from numerous sources specificallydesigned for this purpose. Once the ultra-violet fluorescent dyecontaining composition has been introduced to the refrigeration orair-conditioning apparatus and has been allowed to circulate throughoutthe system, a leak can be found by shining said ultra-violet lamp on theapparatus and observing the fluorescence of the dye in the vicinity ofany leak point.

The present invention further relates to a method of using thecompositions of the present invention for producing refrigeration orheat, wherein the method comprises producing refrigeration byevaporating said composition in the vicinity of a body to be cooled andthereafter condensing said composition; or producing heat by condensingsaid composition in the vicinity of the body to be heated and thereafterevaporating said composition. Where the composition of the presentinvention includes refrigeration or heat transfer fluid composition withan ultra-violet fluorescent dye, and/or a solubilizing agent, therefrigerant or heat transfer fluid component of the composition isevaporated and thereafter condensed to produce refrigeration, orcondensed and thereafter evaporated to produce heat.

Mechanical refrigeration is primarily an application of thermodynamicswherein a cooling medium, such as a refrigerant, goes through a cycle sothat it can be recovered for reuse. Commonly used cycles includevapor-compression, absorption, steam-jet or steam-ejector, and air.

Vapor-compression refrigeration systems include an evaporator, acompressor, a condenser, and an expansion device. A vapor-compressioncycle re-uses refrigerant in multiple steps producing a cooling effectin one step and a heating effect in a different step. The cycle can bedescribed simply as follows. Liquid refrigerant enters an evaporatorthrough an expansion device, and the liquid refrigerant boils in theevaporator at a low temperature to form a gas and produce cooling. Thelow-pressure gas enters a compressor where the gas is compressed toraise its pressure and temperature. The higher-pressure (compressed)gaseous refrigerant then enters the condenser in which the refrigerantcondenses and discharges its heat to the environment. The refrigerantreturns to the expansion device through which the liquid expands fromthe higher-pressure level in the condenser to the low-pressure level inthe evaporator, thus repeating the cycle.

The present invention further relates to a process for producing coolingcomprising evaporating the compositions of the present invention in thevicinity of a body to be cooled, and thereafter condensing saidcompositions.

The present invention further relates to a process for producing heatcomprising condensing the compositions of the present invention in thevicinity of a body to be heated, and thereafter evaporating saidcompositions.

There are various types of compressors that may be used in refrigerationapplications. Compressors can be generally classified as reciprocating,rotary, jet, centrifugal, scroll, screw or axial-flow, depending on themechanical means to compress the fluid, or as positive-displacement(e.g., reciprocating, scroll or screw) or dynamic (e.g., centrifugal orjet), depending on how the mechanical elements act on the fluid to becompressed.

Either positive displacement or dynamic compressors may be used in thepresent inventive process. A centrifugal type compressor is thepreferred equipment for the present refrigerant compositions.

A centrifugal compressor uses rotating elements to accelerate therefrigerant radially, and typically includes an impeller and diffuserhoused in a casing. Centrifugal compressors usually take fluid in at animpeller eye, or central inlet of a circulating impeller, and accelerateit radially outward. Some static pressure rise occurs in the impeller,but most of the pressure rise occurs in the diffuser section of thecasing, where velocity is converted to static pressure. Eachimpeller-diffuser set is a stage of the compressor. Centrifugalcompressors are built with from 1 to 12 or more stages, depending on thefinal pressure desired and the volume of refrigerant to be handled.

The pressure ratio, or compression ratio, of a compressor is the ratioof absolute discharge pressure to the absolute inlet pressure. Pressuredelivered by a centrifugal compressor is practically constant over arelatively wide range of capacities.

Positive displacement compressors draw vapor into a chamber, and thechamber decreases in volume to compress the vapor. After beingcompressed, the vapor is forced from the chamber by further decreasingthe volume of the chamber to zero or nearly zero. A positivedisplacement compressor can build up a pressure, which is limited onlyby the volumetric efficiency and the strength of the parts to withstandthe pressure.

Unlike a positive displacement compressor, a centrifugal compressordepends entirely on the centrifugal force of the high-speed impeller tocompress the vapor passing through the impeller. There is no positivedisplacement, but rather what is called dynamic-compression.

The pressure a centrifugal compressor can develop depends on the tipspeed of the impeller. Tip speed is the speed of the impeller measuredat its tip and is related to the diameter of the impeller and itsrevolutions per minute. The capacity of the centrifugal compressor isdetermined by the size of the passages through the impeller. This makesthe size of the compressor more dependent on the pressure required thanthe capacity.

Because of its high-speed operation, a centrifugal compressor isfundamentally a high volume, low-pressure machine. A centrifugalcompressor works best with a low-pressure refrigerant, such astrichlorofluoromethane (CFC-11) or 1,2,2-trichlorotrifluoroethane(CFC-113).

Large centrifugal compressors typically operate at 3000 to 7000revolutions per minute (rpm). Small turbine centrifugal compressors aredesigned for high speeds, from about 40,000 to about 70,000 (rpm), andhave small impeller sizes, typically less than 0.15 meters (about 6inches).

A multi-stage impeller may be used in a centrifugal compressor toimprove compressor efficiency thus requiring less power in use. For atwo-stage system, in operation, the discharge of the first stageimpeller goes to the suction intake of a second impeller. Both impellersmay operate by use of a single shaft (or axle). Each stage can build upa compression ratio of about 4 to 1; that is, the absolute dischargepressure can be four times the absolute suction pressure. Severalexamples of two-stage centrifugal compressor systems, particularly forautomotive applications, are described in U.S. Pat. No. 5,065,990 andU.S. Pat. No. 5,363,674, both incorporated herein by reference.

The compositions of the present invention suitable for use in arefrigeration, or air-conditioning systems employing a centrifugalcompressor comprise at least one of:

2,2-dimethylbutane;

2,3-dimethylbutane;

2,3-dimethylpentane;

2-methylhexane;

3-methylhexane;

2-methylpentane;

3-ethylpentane;

3-methylpentane;

cyclohexane;

cyclopentane;

n-heptane;

methylcyclopentane;

n-pentane; and

n-hexane.

These above-listed compositions are also suitable for use in amulti-stage centrifugal compressor, preferably a two-stage centrifugalcompressor apparatus.

The compositions of the present invention may be used in stationaryair-conditioning, heat pumps or mobile air-conditioning andrefrigeration systems. Stationary air-conditioning and heat pumpapplications include window, ductless, ducted, packaged terminal,chillers and commercial, including packaged rooftop. Refrigerationapplications include domestic or home refrigerators and freezers, icemachines, self-contained coolers and freezers, walk-in coolers andfreezers and transport refrigeration systems.

The compositions of the present invention may additionally be used inair-conditioning, heating and refrigeration systems that employ fin andtube heat exchangers, microchannel heat exchangers and vertical orhorizontal single pass tube or plate type heat exchangers.

Conventional microchannel heat exchangers may not be ideal for the lowpressure refrigerant compositions of the present invention. The lowoperating pressure and density result in high flow velocities and highfrictional losses in all components. In these cases, the evaporatordesign may be modified. Rather than several microchannel slabs connectedin series (with respect to the refrigerant path) a single slab/singlepass heat exchanger arrangement may be used. Therefore, a preferred heatexchanger for the low pressure refrigerants of the present invention isa single slab/single pass heat exchanger.

In addition to two-stage or other multi-stage centrifugal compressorapparatus, the following compositions of the present invention aresuitable for use in refrigeration or air-conditioning apparatusemploying a single slab/single pass heat exchanger:

2,2-dimethylbutane;

2,3-dimethylbutane;

2,3-dimethylpentane;

2-methylhexane;

3-methylhexane;

2-methylpentane;

3-ethylpentane;

3-methylpentane;

cyclohexane;

cyclopentane;

n-heptane;

methylcyclopentane;

n-pentane;

n-hexane; and combinations thereof.

The compositions of the present invention are particularly useful insmall turbine centrifugal compressors (mini-centrifugal compressors),which can be used in auto and window air-conditioning, heat pumps, ortransport refrigeration, as well as other applications. These highefficiency mini-centrifugal compressors may be driven by an electricmotor and can therefore be operated independently of the engine speed. Aconstant compressor speed allows the system to provide a relativelyconstant cooling capacity at all engine speeds. This provides anopportunity for efficiency improvements especially at higher enginespeeds as compared to a conventional R-134a automobile air-conditioningsystem. When the cycling operation of conventional systems at highdriving speeds is taken into account, the advantage of these lowpressure systems becomes even greater.

Alternatively, rather than use electrical power, the mini-centrifugalcompressor may be powered by an engine exhaust gas driven turbine or aratioed gear drive assembly with ratioed belt drive. The electricalpower available in current automobile design is about 14 volts, but thenew mini-centrifugal compressor requires electrical power of about 50volts. Therefore, use of an alternative power source would beadvantageous. A refrigeration or air-conditioning apparatus powered byan engine exhaust gas driven turbine is described in detail in U.S.provisional patent application No. 60/658,915, filed Mar. 4, 2005,incorporated herein by reference. A refrigeration or air-conditioningapparatus powered by a ratioed gear drive assembly is described indetail in U.S. provisional patent application No. 60/663924, filed Mar.21, 2005, incorporated herein by reference.

The present invention further relates to a process to produce coolingcomprising compressing a composition of the present invention, in amini-centrifugal compressor powered by an engine exhaust gas driventurbine; condensing said composition; and thereafter evaporating saidcomposition in the vicinity of a body to be cooled.

The present invention further relates to a process to produce coolingcomprising compressing a composition of the present invention, in amini-centrifugal compressor powered by a ratioed gear drive assemblywith a ratioed belt drive; condensing said composition; and thereafterevaporating said composition in the vicinity of a body to be cooled.

Some of the low pressure refrigerant fluids of the present invention maybe suitable as drop-in replacements for CFC-113 in existing centrifugalequipment.

The present invention further relates to a method for replacing CFC-113in existing refrigeration apparatus or air-conditioning apparatus, saidmethod comprising providing a composition of the present invention asthe replacement.

The present invention further relates to a process for transfer of heatfrom a heat source to a heat sink wherein the compositions of thepresent invention serve as heat transfer fluids. Said process for heattransfer comprises transferring the compositions of the presentinvention from a heat source to a heat sink.

Heat transfer fluids are utilized to transfer, move or remove heat fromone space, location, object or body to a different space, location,object or body by radiation, conduction, or convection. A heat transferfluid may function as a secondary coolant by providing means of transferfor cooling (or heating) from a remote refrigeration (or heating)system. In some systems, the heat transfer fluid may remain in aconstant state throughout the transfer process (i.e., not evaporate orcondense). Alternatively, evaporative cooling processes may utilize heattransfer fluids as well.

A heat source may be defined as any space, location, object or body fromwhich it is desirable to transfer, move or remove heat. Examples of heatsources may be spaces (open or enclosed) requiring refrigeration orcooling, such as refrigerator or freezer cases in a supermarket,building spaces requiring air-conditioning, or the passenger compartmentof an automobile requiring air-conditioning. A heat sink may be definedas any space, location, object or body capable of absorbing heat. Avapor compression refrigeration system is one example of such a heatsink.

EXAMPLES Example 1 Tip Speed to Develop Pressure

Tip speed can be estimated by making some fundamental relationships forrefrigeration equipment that use centrifugal compressors. The torque animpeller ideally imparts to a gas is defined asT=m*(v ₂ *r ₂ −v ₁ *r ₁)   Equation 1where

T=torque, Newton-meters

m=mass rate of flow, kg/sec

v₂=tangential velocity of refrigerant leaving impeller (tip speed),meters/sec

r₂=radius of exit impeller, meters

v₁=tangential velocity of refrigerant entering impeller, meters/sec

r₁=radius of inlet of impeller, meters

Assuming the refrigerant enters the impeller in an essentially axialdirection, the tangential component of the velocity v₁=0, thereforeT=m*v ₂ *r ₂   Equation 2

The power required at the shaft is the product of the torque and therotative speedP=T*ω  Equation 3where

P=power, W

ω=angular velocity, radians/s

therefore,P=T*w=m*v ₂ *r ₂*ω  Equation 4

At low refrigerant flow rates, the tip speed of the impeller and thetangential velocity of the refrigerant are nearly identical; thereforer ₂ *w=v ₂   Equation 5andP=m*v ₂ *v ₂   Equation 6

Another expression for ideal power is the product of the mass rate offlow and the isentropic work of compression,P=m*H _(i)*(1000 J/kJ)   Equation 7where

H_(i)=Difference in enthalpy of the refrigerant from a saturated vaporat the evaporating conditions to saturated condensing conditions, kJ/kg.

Combining the two expressions Equation 6 and 7 produces,v ₂ *v ₂=1000*H _(i)   Equation 8

Although Equation 8 is based on some fundamental assumptions, itprovides a good estimate of the tip speed of the impeller and providesan important way to compare tip speeds of refrigerants.

The table below shows theoretical tip speeds that are calculated for1,2,2-trichlorotrifluoroethane (CFC-113) and 3-ethylpentane of thepresent invention. The conditions assumed for this comparison are:Evaporator temperature 40.0° F. (4.4° C.) Condenser temperature 110.0°F. (43.3° C.) Liquid subcool temperature 10.0° F. (5.5° C.) Return gastemperature  75.0° F. (23.8° C.) Compressor efficiency is 70%

These are typical conditions under which small turbine centrifugalcompressors perform. TABLE 2 Hi Hi*0.7 Hi*0.7 V2 V2 rel CompositionBtu/lb Btu/lb KJ/Kg m/s to CFC-113 CFC-113 10.92 7.6 17.8 133.3 na3-ethylpentane 14.54 10.2 23.7 153.9 115%

Example 2 Performance Data

The following table shows the performance of various refrigerantscompared to CFC-113, by showing evaporator and condenser pressures,compressor discharge temperature, COP (energy efficiency) and capacity(Cap). The data are based on the following conditions. Evaporatortemperature 40.0° F. (4.4° C.) Condenser temperature 110.0° F. (43.3°C.) Subcool temperature 10.0° F. (5.5° C.) Return gas temperature  75.0°F. (23.8° C.) Compressor efficiency is 70%

TABLE 3 Comp Comp Evap Evap Cond Cond Disch Disch Pres Pres Pres PresTemp Temp Cap Cap Compound (Psia) (kPa) (Psia) (kPa) (F.) (C.) COP(Btu/min) (kW) CFC-113 2.7 19 12.8 88 156.3 69.1 4.18 14.8 0.262,2-dimethylbutane 2.7 18 11.8 81 137.8 58.8 4.07 15.4 0.272,3-dimethylbutane 1.9 13 8.9 62 138.3 59.1 4.08 11.4 0.202,3-dimethylpentane 0.5 3 3.0 21 141.8 61.0 4.15 3.6 0.06 2-methylbutane6.0 41 23.9 165 146.3 63.5 4.11 32.6 0.57 2-methylhexane 0.5 3 2.9 20142.3 61.3 4.15 3.4 0.06 2-methylpentane 1.7 11 8.2 57 143.7 62.1 4.1410.5 0.18 3-ethylpentane 0.4 3 2.6 18 143.1 61.7 4.16 3.0 0.053-methylhexane 0.4 3 2.7 19 142.8 61.6 4.15 3.2 0.06 3-methylpentane 1.510 7.4 51 144.4 62.4 4.15 9.5 0.17 cyclohexane 0.7 5 4.1 28 151.2 66.24.23 5.1 0.09 cyclopentane 2.6 18 11.8 82 155.7 68.7 4.24 16.1 0.28n-heptane 0.3 2 2.1 14 144.8 62.7 4.17 2.4 0.04 n-hexane 1.1 8 6.1 42146.2 63.4 4.16 7.6 0.13 methylcyclopentane 1.1 7 5.6 38 149.3 65.2 4.217.1 0.12 n-pentane 4.4 30 18.7 129 152.6 67.0 4.17 25.5 0.45

Data show the compositions of the present invention have evaporator andcondenser pressures similar to CFC-113. Some compositions also havehigher capacity or energy efficiency than CFC-113.

1. A refrigerant or heat transfer fluid composition comprising at leastone hydrocarbon selected from the group consisting of:2,2-dimethylbutane; 2,3-dimethylbutane; 2,3-dimethylpentane;2-methylhexane; 3-methylhexane; 2-methylpentane; 3-ethylpentane;3-methylpentane; cyclohexane; cyclopentane; n-heptane;methylcyclopentane; n-pentane; and n-hexane.
 2. A refrigerant or heattransfer fluid composition suitable for use in refrigeration orair-conditioning apparatus employing (i) centrifugal compressor or (ii)multi-stage centrifugal compressor or (iii) single slab/single pass heatexchanger, said composition comprising at least one hydrocarbon selectedfrom the group consisting of: 2,2-dimethylbutane; 2,3-dimethylbutane;2,3-dimethylpentane; 2-methylhexane; 3-methylhexane; 2-methylpentane;3-ethylpentane; 3-methylpentane; cyclohexane; cyclopentane; n-heptane;methylcyclopentane; n-pentane; and n-hexane.
 3. A process for producingcooling, said process comprising evaporating the composition of claim 1or 2 in the vicinity of a body to be cooled, and thereafter condensingsaid composition.
 4. A process for producing heat, said processcomprising condensing the composition of claim 1 or 2 in the vicinity ofa body to be heated, and thereafter evaporating said composition.
 5. Amethod of using the compositions of claim 1 or 2, for heat transfer,said method comprising transferring said composition from a heat sourceto a heat sink.
 6. The composition of claim 1, further comprising atleast one ultra-violet fluorescent dye selected from the groupconsisting of naphthalimides, perylenes, coumarins, anthracenes,phenanthracenes, xanthenes, thioxanthenes, naphthoxanthenes,fluoresceins, and derivatives thereof.
 7. The composition of claim 6,further comprising at least one solubilizing agent selected from thegroup consisting of hydrocarbons, dimethylether, polyoxyalkylene glycolethers, amides, ketones, nitriles, chlorocarbons, esters, lactones, arylethers, fluoroethers, and 1,1,1-trifluoroalkanes; and wherein therefrigerant and solubilizing agent may not be the same compound.
 8. Thecomposition of claim 7, wherein said solubilizing agent is selected fromthe group consisting of: a) polyoxyalkylene glycol ethers represented bythe formula R¹[(OR²)_(x)OR³]_(y), wherein: x is an integer from 1 to 3;y is an integer from 1 to 4; R¹ is selected from hydrogen and aliphatichydrocarbon radicals having 1 to 6 carbon atoms and y bonding sites; R²is selected from aliphatic hydrocarbylene radicals having from 2 to 4carbon atoms; R³ is selected from hydrogen, and aliphatic and alicyclichydrocarbon radicals having from 1 to 6 carbon atoms; at least one of R¹and R³ is selected from said hydrocarbon radicals; and wherein saidpolyoxyalkylene glycol ethers have a molecular weight of from about 100to about 300 atomic mass units; b) amides represented by the formulaeR¹CONR²R³ and cyclo-[R⁴CON(R⁵)—], wherein R¹, R², R³ and R⁵ areindependently selected from aliphatic and alicyclic hydrocarbon radicalshaving from 1 to 12 carbon atoms, and at most one aromatic radicalhaving from 6 to 12 carbon atoms; R⁴ is selected from aliphatichydrocarbylene radicals having from 3 to 12 carbon atoms; and whereinsaid amides have a molecular weight of from about 100 to about 300atomic mass units; c) ketones represented by the formula R¹COR², whereinR¹ and R² are independently selected from aliphatic, alicyclic and arylhydrocarbon radicals having from 1 to 12 carbon atoms, and wherein saidketones have a molecular weight of from about 70 to about 300 atomicmass units; d) nitriles represented by the formula R¹CN, wherein R¹ isselected from aliphatic, alicyclic or aryl hydrocarbon radicals havingfrom 5 to 12 carbon atoms, and wherein said nitriles have a molecularweight of from about 90 to about 200 atomic mass units; e) chlorocarbonsrepresented by the formula RCl_(x), wherein; x is selected from theintegers 1 or 2; R is selected from aliphatic and alicyclic hydrocarbonradicals having from 1 to 12 carbon atoms; and wherein saidchlorocarbons have a molecular weight of from about 100 to about 200atomic mass units; f) aryl ethers represented by the formula R¹OR²,wherein: R¹ is selected from aryl hydrocarbon radicals having from 6 to12 carbon atoms; R² is selected from aliphatic hydrocarbon radicalshaving from 1 to 4 carbon atoms; and wherein said aryl ethers have amolecular weight of from about 100 to about 150 atomic mass units; g)1,1,1-trifluoroalkanes represented by the formula CF₃R¹, wherein R¹ isselected from aliphatic and alicyclic hydrocarbon radicals having fromabout 5 to about 15 carbon atoms; h) fluoroethers represented by theformula R¹OCF₂CF₂H, wherein R¹ is selected from aliphatic and alicyclichydrocarbon radicals having from about 5 to about 15 carbon atoms; orwherein said fluoroethers are derived from fluoro-olefins and polyols,wherein said fluoro-olefins are of the type CF₂═CXY, wherein X ishydrogen, chlorine or fluorine, and Y is chlorine, fluorine, CF₃ orOR_(f), wherein R_(f) is CF₃, C₂F₅, or C₃F₇; and said polyols are linearor branched, wherein said linear polyols are of the typeHOCH₂(CHOH)_(x)(CRR′)_(y)CH₂OH, wherein R and R¹ are hydrogen, CH₃ orC₂H₅, x is an integer from 0-4, y is an integer from 0-3 and z is eitherzero or 1, and said branched polyols are of the typeC(OH)_(t)(R)_(u)(CH₂OH)_(v)[(CH₂)_(m)CH₂OH]_(w), wherein R may behydrogen, CH₃ or C₂H₅, m is an integer from 0 to 3, t and u are 0 or 1,v and w are integers from 0 to 4, and also wherein t+u+v+w=4; i)lactones represented by structures [B], [C], and [D]:

wherein, R₁ through R₈ are independently selected from hydrogen, linear,branched, cyclic, bicyclic, saturated and unsaturated hydrocarbylradicals; and the molecular weight is from about 100 to about 300 atomicmass units; and j) esters represented by the general formula R¹CO₂R²,wherein R¹ and R² are independently selected from linear and cyclic,saturated and unsaturated, alkyl and aryl radicals; and wherein saidesters have a molecular weight of from about 80 to about 550 atomic massunits.
 9. A method for introducing an ultraviolet fluorescent dye into acompression refrigeration or air-conditioning apparatus, said methodcomprising dissolving the ultraviolet fluorescent dye in the compositionof claim 1 or 2, in the presence of a solubilizing agent, andintroducing the combination into said compression refrigeration orair-conditioning apparatus.
 10. A method for solubilizing ultravioletfluorescent dye in the composition of claim 1 or 2, said methodcomprising contacting the ultraviolet fluorescent dye with saidcomposition, in the presence of a solubilizing agent.
 11. A method fordetecting leaks, said method comprising using the composition of claim 6in a compression refrigeration or air-conditioning apparatus, providingsaid apparatus, and providing a suitable means for detecting saidcomposition in the vicinity of said apparatus.
 12. A method of producingcooling, said method comprising: evaporating the refrigerant or heattransfer fluid component of the composition of claim 6 in the vicinityof a body to be cooled and thereafter condensing said refrigerant orheat transfer fluid component.
 13. A method of producing heat, saidmethod comprising: condensing the refrigerant or heat transfer fluidcomponent of the composition of claim 6 in the vicinity of the body tobe heated and thereafter evaporating said refrigerant or heat transferfluid component.
 14. The composition of claim 1 or 6 further comprisinga stabilizer, water scavenger, or odor masking agent.
 15. Thecomposition of claim 14 wherein said stabilizer is selected from thegroup consisting of nitromethane, hindered phenols, hydroxylamines,thiols, phosphites and lactones.
 16. A method of using the compositionof claim 1 or 2, wherein said method comprises producing heat orrefrigeration in a refrigeration or air-conditioning apparatus employinga multi-stage centrifugal compressor.
 17. The method of claim 16 whereinsaid multi-stage centrifugal compressor is a two-stage centrifugalcompressor.
 18. The composition of claim 14 wherein said water scavengeris an ortho ester.
 19. A process to produce cooling comprisingcompressing a composition of claim 1 or 2, in a mini-centrifugalcompressor powered by an engine exhaust gas driven turbine; condensingsaid composition; and thereafter evaporating said composition in thevicinity of a body to be cooled.
 20. A process to produce coolingcomprising compressing a composition of claim 1 or 2 in amini-centrifugal compressor powered by a ratioed gear drive assemblywith a ratioed belt drive; condensing said composition; and thereafterevaporating said composition in the vicinity of a body to be cooled. 21.A method for replacing CFC-113 in existing refrigeration apparatus orair-conditioning apparatus, said method comprising providing acomposition of claim 1 as the replacement.